In recent years, hang-gliding has captured the imagination of several aviation buffs. In the early years, hang-gliding required a mountain side or a cliff from which to launch. Hence, the sport was geographically limited. It was not long, however, before enthusiasts of the sport added engines so that flatlanders could participate. Powered hang-gliders have become to be known as ultralight aircraft.
In the United States, ultralight aircraft remain unregulated as long as the device is foot-launchable, even though landing gear may be present for convenience.
Early models of ultralight aircraft used a direct drive connection between the engine and the propellor. Often, power was limited with these units, and the rate of climb was slow. More recently, engine power and speed have been increased by correspondingly reducing rotative speed between the engine and the propellor with pulleys and belts.
The sport of power hang-gliding or the flying of ultralight aircraft has been and remains, however, extremely dangerous. Several pilots have crashed to their deaths. Successful flight has been described as an art since weight must be shifted rapidly as wind gusts or drafts affect the wing foils or as propellor thrust varies according to movement of the engine throttle. Present ultralight aircrafts have the further problem that as the throttle is varied, not only does the magnitude of the thrust change, but also the direction of the thrust line changes. The present invention was developed in response to this latter problem. It should be pointed out, however, that, regardless of the reason spawning its development, the present invention has application in areas not related to ultralight aircraft. For example, powerplants comprised of engines driving propellors while attached to a frame are used in conjunction with smoke generators during frost periods in fruit orchards.